I couldn't disagree more about your impressions of the S4. Although I realize it is your impression and you were clear that user experience will vary, I still can't wrap my head around the sibilance you are hearing. I have read plenty of reviews for the S4, plenty of good, very few bad, and of all of them, the cons listed never included sibilance. I've been using the S4 for well over a year and have bought a second pair because I enjoyed them so much (and I am not a basshead!) I guess I am a bit surprised by your impressions ... sibilance ..?? Our ears must differ radically.